Polymeric Pharmaceutical Coating Materials I Preparation and Properties

Lappas, Lewis C.; McKeehan, Wayne

doi:10.1002/jps.2600540203

Cited by 46 publications

(6 citation statements)

References 7 publications

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“…One desirable attribute of these coatings was the ability to not dissolve until the drug substance reached the intestines, where the pH is mostly neutral or alkaline. Indeed, most commercially available enteric coating agents of both cellulose and acrylic polymers are designed to be soluble in the pH range from 5.0 to 7.0 (18,19). This lack of solubility at low pH (3.5 to 5.5) was a desired goal in the selection of HPMCP and CAP for use as enteric coatings.…”

Section: Discussionmentioning

confidence: 99%

Critical Design Features of Phenyl Carboxylate-Containing Polymer Microbicides

Rando¹,

Obara

Osterling

et al. 2006

Antimicrob Agents Chemother

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Recent studies of cellulose-based polymers substituted with carboxylic acids like cellulose acetate phthalate (CAP) have demonstrated the utility of using carboxylic acid groups instead of the more common sulfate or sulfonate moieties. However, the pK a of the free carboxylic acid group is very important and needs careful selection. In a polymer like CAP the pK a is approximately 5.28. This means that under the low pH conditions found in the vaginal lumen, CAP would be only minimally soluble and the carboxylic acid would not be fully dissociated. These issues can be overcome by substitution of the cellulose backbone with a moiety whose free carboxylic acid group(s) has a lower pK a . Hydroxypropyl methylcellulose trimellitate (HPMCT) is structurally similar to CAP; however, its free carboxylic acids have pK a s of 3.84 and 5.2. HPMCT, therefore, remains soluble and molecularly dispersed at a much lower pH than CAP. In this study, we measured the difference in solubility and dissociation between CAP and HPMCT and the effect these parameters might have on antiviral efficacy. Further experiments revealed that the degree of acid substitution of the cellulose backbone can significantly impact the overall efficacy of the polymer, thereby demonstrating the need to optimize any prospective polymer microbicide with respect to pH considerations and the degree of acid substitution. In addition, we have found HPMCT to be a potent inhibitor of CXCR4, CCR5, and dual tropic strains of human immunodeficiency virus in peripheral blood mononuclear cells. Therefore, the data presented herein strongly support further evaluation of an optimized HPMCT variant as a candidate microbicide.

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Section: Discussionmentioning

confidence: 99%

Critical Design Features of Phenyl Carboxylate-Containing Polymer Microbicides

Rando¹,

Obara

Osterling

et al. 2006

Antimicrob Agents Chemother

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“…The screening and testing of polymers as potential film coatings were the subjects of a number of investigations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). In these studies, films were evaluated on the basis of their performance on film-coated tablets or as free unsupported films.…”

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confidence: 99%

Free Films I: Apparatus and Preliminary Evaluation

Allen

DeMarco

Kwana³

1972

Journal of Pharmaceutical Sciences

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“…(8) produced entcric disintegration properties from tablets coated with styrene-malcic acid copolymers. Lappas and McKeehan (9) found that partial esters of poly(methy1 vinyl ethermaleic anhydride) might be suitable to control the release of drugs upon reaching a specific intestinal pH. Further studies (10) showed that some control of in oioo initial drug release could be obtained from such partial esters when applied as coatings to solid dosage forms.…”

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confidence: 99%